WO2007085577A9

WO2007085577A9 - Electric power transmission line

Info

Publication number: WO2007085577A9
Application number: PCT/EP2007/050573
Authority: WO
Inventors: Massimo Cresta; Alberto Geri
Original assignee: Massimo Cresta; Alberto Geri
Priority date: 2006-01-24
Filing date: 2007-01-21
Publication date: 2007-09-20
Also published as: EP1977490A1; ITRM20060031A1; WO2007085577A1

Abstract

An electrical power transmission line (1) allows the displacement of drawing off members whose position is not decided in the design process and comprises: a plurality of tubular conductive members (2, 3, 4, 5) concentric with a symmetry at least rectangular; and drawing off means for the electrical power having, at each conductive member (2, 3, 4, 5), a respective longitudinal discontinuity region (6, 7, 8, 9) and drawing off members to be connected to each conductive member (2, 3, 4, 5), displaceable together at any point along said discontinuity region (6, 7, 8, 9), keeping the symmetry with respect to the same longitudinal symmetry plane.

Description

Electric Power Transmission Line

DESCRIPTION

The present invention relates to an electric power transmission line for the distribution of electrical power, comprising a plurality of tubular conductive members which are substantially concentric with respect to a longitudinal axis. They are electrically insulated one to each other and they show, according to a cross- sectional view by a plane orthogonal to said longitudinal axis, a symmetry which is at least rectangular. Further, this kind of electric power transmission line comprises drawing off means for the electrical power from each conductive member, having a respective drawing off member to be connected to each corresponding conductive member.

Examples of electric power transmission lines, which can fall within the above preamble, are disclosed in European Patent Applications Nos. EP- 0,788,208-A and EP- 1,085,632-A, in US Patent Application No. US- 2004/0074664-A and in US Patent No. 3,569,606-A.

The features characterising the above patent documents are: the geometry, which has exclusively a cylindrical symmetry; and the possibility to establish a power supply

(i.e. the electrical power drawing off) only at prearranged points fixed once in the design process.

The above mentioned two features make the electric power transmission lines of said prior citations hard to carry out and to use, due both to the structural complexity of the system and to the inflexibility thereof with respect to the supply extraction points. Hence, they prove themselves unsuited for the carrying out of electric power distribution switchboards or of any comparable structure . The technical problem at the root of the present invention is to devise an electric power transmission line allowing to obviate the drawbacks mentioned with reference to the prior art.

This problem is solved by an electric power transmission line as above specified, characterised in that said drawing off means comprises, at each conductive member, a respective longitudinal discontinuity region, said discontinuity regions extending along a significant portion of the electric power transmission line and being respectively symmetric with respect to the same longitudinal symmetry plane, the drawing off members, which provide an electric power supply, being displaceable at any point along said discontinuity regions, thus keeping said symmetry with respect to said same longitudinal symmetry plane.

The electric power transmission line, which embodies the present invention, collects the well-known benefits of the axial symmetric systems, wherein the electrodynamic stresses in short-circuit conditions and the electromagnetic emission are reduced, and the easiness in the construction, being usable, for the manufacture thereof, fully-automated and low-technology content industrial manufacturing processes followed by the simple assembling of the related components, and the flexibility in the working out of the conventional systems currently in use, having assemblies of rods displaced side-by-side, commonly laid on a plane, from which it is possible to branch off an electrical power supply in every point thereof without any interruption.

Therefore, the main advantage allowed by the present invention with respect to the prior art is achieved by the possibility of drawing off electrical power through a drawing off system whose position is not necessarily decided once in the design or manufacturing process but in the working out of the assembly employing the electrical power transmission line.

The present invention is herein described according to some preferred embodiments thereof, together with some preferred applications thereof, explained to an illustrative and non-limitative purpose with reference to the following examples and to the annexed drawings wherein:

* figure 1 is a schematic and perspective view of a first embodiments of electric power transmission line according to the invention;

* figure 2 is an enlarged perspective view of a portion of the electric power transmission line of figure 1 ;

* figure 3 is a cross-sectional view of the electric power transmission line of figure 1 ;

* figure 4 is the linking device of the wiring to the electric power transmission line;

* figure 5 is a schematic and perspective view of a second embodiment of the electric power transmission line according to the invention;

* figure 6 is a cross-sectional view of the electric power transmission line of figure 5;

* figure 7 is a schematic and perspective view of a third embodiment of the electric power transmission line according to the invention;

* figure 8 is a cross-sectional view of the electric power transmission line of figure 7 ;

* figure 9 is a schematic and perspective view of a fourth embodiment of the electric power transmission line according to the invention;

* figure 10 is a cross-sectional view of a variation in the fourth embodiment of figure 9;

* figures 11a and lib are perspective views of a details in the fourth embodiment of electric power transmission line; and

* figures 12 to 15 illustrate a possible assembling of an electric power transmission line according to the present invention.

With reference to the drawings, an electric power transmission line is described through some embodiments thereof, all of them indicated by 1. In the following, identical or analogous elements in different embodiments are indicated by the same reference numeral.

All the electric power transmission lines of the following embodiments are represented as having four tubular conductive members, substantially concentric with respect to a longitudinal axis, but it is intended that such a solution, suitable for the distribution of three- phase alternate current with a neutral conductor (3F+N) , can be modified so as to employ multiple tubular conductors (i.e., 1, 2 or n conductors) in direct current bipolar systems, or in alternate current systems as well, either of single-phase type (i.e., phase-neutral, FN, o phase-phase, FF, with or without protection conductor, PE - FN+ (PE) o FF+ (PE) -) or of poly-phase type (i.e., n phases with or without neutral and/or PE - nF+ (N) +(PE) - ) . All these variants have in common the capability of compensating the magnetic fields generated by the single conductors passed through by current both in a stationary and a nearly-stationary state or a transitory state, eliminating or drastically relieving the levels of generated magnetic field or the possible radiated electromagnetic disturbances, as well as the electromechanical stresses among the metallic conductive members .

All the conductive members are made in a suitable conductive material which is not specified because it is irrelevant in view of the object of the invention.

The pass-through section of each conductive member can be either uniform, for having the same linear resistance along each conductor, or variable from the inner to the outer, for decreasing the thermal stresses of the electric power transmission line. However, for the sake of simplicity, in the annexed drawings the pass-through sections have been depicted apart from these possible options, because believed not essential for the graphical representation of the electric power transmission line.

At last, it is intended that the innermost member can be either massive or hollow, both solutions being perfectly equivalent to each other.

With reference to figures 1 to 3, a first example of electric power transmission line 1 is constituted by four tubular conductive members, concentric with respect to a longitudinal axis A, respectively indicated by 2, 3, 4 and 5 from the innermost to the outermost.

They are electrically insulated one to each other, due to an air gap or to the interposition of insulating sheets with the exclusive task of increasing the insulating resistance among the conductors. Further, they show, in a cross-sectional view according to a plane orthogonal to said longitudinal axis A, a rectangular symmetry. The tubes may have triangular, square, rectangular, polygonal or even circular sections.

The square and rectangular shapes are suitable to be produced by bending of a sheet in conductive material having a proper thickness, or even by extrusion, the latter being a solution adoptable even for sections with an anyhow complex shape.

The electric power transmission line 1 comprises drawing off means for the electric power from each conductive member 2, 3, 4 and 5.

Said drawing off moar.s coirj_rijcs, at each conductive member 2, 3, 4 and D, a respective longitudinal discontinuity region which, in the present embodiment, is constituted , except for the inner conductive member, by a longitudinal continuous slot having a uniform width.

Such a slot, respectively indicated by 6, 7 and 8, extends along a significant part of electric power transmission line 1 length, even along the whole length thereof. It, being placed at the centre of a surface of each conductive member 3, 4, 5, is symmetric according to the same longitudinal symmetry plane. Said slot could be also placed at a corner and hence touching two adjacent surfaces of each conductive element, thus keeping the symmetry thereof according to the same longitudinal symmetry plane.

In connection with the innermost conductive member 2, the discontinuity region is constituted by a connection line, for instance a longitudinal welding 9, with a first drawing off member 10 here embodied by a flat plate extending perpendicularly to and longitudinally fixed to the conductive member 2 surface , i.e. to the electrical power transmission line 1.

The first drawing off member 10 extends to the exterior of the electrical power transmission line 1, i.e. beyond the outermost conductive member 5, and it is insulated, at the opposite faces thereof, by first insulating layers 11 leaving uncovered the end 12 of the first drawing off member 10.

The first drawing off member 10 and the respective insulating layers 11 thereof project from the electrical power transmission line 1 through the slots 6, ⁷ a:,d 8, tr_c letter having an appropriate _cngrh.

Second drawing off members 13 are placed outside said first insulating layers 11, connected to the subsequent conductive member 3. In turn, at the external surfaces thereof, they are covered by a second insulating layer 14.

Similarly, the subsequent conductive member 4 has third drawing off members 15 and third insulating layers 16 encasing the preceding drawing off members and insulating layers, all of them being symmetric with respect to the symmetry plane of the above mentioned discontinuity regions 6, 7, 8 and 9. Further, the outermost conductive member 5 is provided by fourth drawing off members 17 arranged so as to cover said third insulating layers 16.

Each system embodied by one drawing off member and by the respective conductive member can be manufactured either by welded components or in an integral component by bent sheets or by extrusion.

The drawing off members 10, 13, 15, 17, all shaped as a flat plate extending perpendicularly to the surfaces of the respective conductive member 2, 3, 4, 5 and longitudinally fixed to the electrical power transmission line 1, and the respective insulating layers 11, 14, 16 are arranged so as to leave uncovered one outward end of each drawing off member 10, 13, 15, 17.

Therefore, such uncovered ends have, along the whole extension thereof, the shape of continuous strips to which contact members 23 are welded or integrally formed, i.e. by extrusion, whose sections, in the present embodiment, are C-shaped with flat faces turned toward said strips. With reference to figure 4, it is apparent that it is possible to draw electrical power through the contact members 23, e.g. by virtue of a bolt 19 with an appropriately shaped head for allowing it to be locked by the contact member 23. The tightening of a nut 20 fixes the bolt 19 inside the recess thereof, and allows the mounting by pressure of the conductive wiring 21.

Bolts 19 and nuts 20 can be freely displaced in every point along the contact elements 23 of the electrical power transmission line 1. The conductor members 2, 3, 4, 5, the respective drawing off members 10, 13, 15, 17 and the contact member 23 for the mounting of conductive wiring 21 are held in their respective position by a suitable insulated bearings 24, conveniently shaped and perforated, longitudinally divided in two symmetric parts .

Holes 18, 25 allow the tightening of the insulated bearings to the contact members 23, integral with the drawing off plates 10, 13, 15, 17, and accordingly to the conductive members 2, 3, 4, 5 to assemble the overall structure by the use of a tie-rod inserted in the hole 18. All the above arrangement is provided for giving mechanical strength to the structure of the electrical power transmission line 1, and for ensuring the proper air insulating gaps among the conductive members 2, 3, 4, 5.

In such a way, the insulated bearings 24 and the drawing off members 10, 13, 15, 17, in cooperation with the insulating layers 11, 14, 16, also act as mounting means of the electrical power transmission line 1.

According to a variant of the above embodiment, if the air insulation is not sufficient according to the electrical power transmission line standards, a gap 26 among the conductive members 2, 3, 4 and 5 is either filled with a dielectric material, solid or gasiform, or maintained under vacuum.

According to another variant, aeration holes could be formed in the conductive members 2, 3, 4, 5 or a refrigeration fluid forced circulation system could be provided, e.g. operated with air.

With reference to figures 5 and 6, a second embodiment of the electrical power transmission line 1 is consistently similar to the preceding one, with the exclusion of the insulating layers.

The drawing off members 10, 13, 15, and 17 are separated by a further gap 27.

Moreover, at each drawing off strip 18, 19, 20 except for the external one, insulating spacer members 28 are present, made of a material having a proper mechanical and dielectric strength, inserted between the drawing off plates 10, 13, 15, 17 and acting for spacing and assembling them.

In this way, the drawing off members 10, 13, 15, 17 or at least a part of them can be easily originally manufactured by extrusion.

A third embodiment of electrical power transmission line 1 is shown in figures 7 and 8, partly similar to the preceding ones. The conductive members 2, 3, 4 and 5 have a rectangular section and, with the exception of the inner conductive member 2, are built without a wall at the drawing off surface 22. At the latter, each conductive member has a fin 29 projecting inward, operating as a drawing off strip and comprising contact elements 23 welded or extruded. In this embodiment, said fins 29 and the open surface of the inner conductive elements 2 are part of the drawing off means.

The conductive members 2, 3, 4, 5, the respective fins 29 and the contact elements 23 are kept in their position by a suitable insulated support 24 shaped and perforated with holes, allowing the tightening of the insulated bearings 24 to the contact elements 23, which are integral with the fins 29 and consequently with the conductive members 2, 3, 4, 5 for assembling the overall structure, provided for giving mechanical strength to the electrical power transmission line 1 for ensuring the air insulation distances between said conductive members 2, 3, 4, 5.

With reference to figure 8, a fourth embodiment of the electrical power transmission line 1 is shown: the discontinuity regions are formed by longitudinal slots on all the conductive members 2, 3, 4, 5.

With reference to figure 10 showing another version of the fourth embodiment, the slots are formed on opposite surfaces of the electrical power transmission line 1. In both the embodiments, the slots have a uniform width.

In the embodiments of figures 10 and 11, the drawing off means comprises a contact member 30 substantially T- shaped (see figure 10) .

This contact member 30 is apt to be locked at any point of the slot of one of the conductive members. To this purpose the contact member 30 comprises a head 31 contacting the edges 36 of the slot, in such a way acting as contacting strip, and a stem 32, projecting from the electrical power transmission line to be linked to an electrical wiring.

Along the stem 32 a locking member 33 slides for tightening, in cooperation with the head 31, the edges of the respective slot. To this purpose, threaded holes 34 can be provided.

The above drawing off device can assume different shapes in connection with the different phases to which it is linked, however performing its task as above described.

The contact between the stem 32 and the conductive members 2, 3, 4, 5 can be prevented thanks to suitable insulating collars 35, fitted along the stem 32 and properly shaped.

In all the above described embodiments, the drawing off members, serving for extracting the electrical power, can be displaced at any point along the discontinuity regions, but keeping the symmetry with respect to a longitudinal plane comprising the line axis.

With reference to figures 12 to 15, a possible installation plan is disclosed for a distribution switchboard employing the electrical power transmission line according to one of the previously described embodiments.

The distribution switchboard 40 has a system with a pair of upper rods 41 and lower rods 42, all coaxial and with a rectangular symmetry, linked by vertical transmission lines .

At the beginning, the installation provides that the phases, i.e. the three inner conductive members 2, 3 e 4 and the neutral member, i.e. the outer conductive member, are not linked (see figure 11) .

Then, the linking is provided starting from the inner phase (figure 12), to the outer ones (figures 13 and 14) up to the outermost neutral conductor, the last to be connected (figure 15) .

It is intended that, in different arrangements, the neutral conductor could be embodied by the innermost conductive member.

To the above embodiments of electrical power transmission line a man skilled in the art, to meet further and incidental requirements, can introduce several further modifications and changes, however all falling within the protection scope of the present invention, as defined by the annexed claims.

Claims

1. Electrical power transmission line (1) for the distribution of electrical power, comprising:

* a plurality of tubular conductive members (2, 3, 4, 5) , substantially concentric with respect to a longitudinal axis (A) and electrically insulated one to each other, having, in a cross-sectional view according to a plane orthogonal to said longitudinal axis (A) , a symmetry at least rectangular; and

* drawing off means for the electrical power from each conductive member (2, 3, 4, 5), having a respective drawing off member (10, 13, 15, 17) to be connected to each conductive member (2, 3, 4, 5),

characterised in that said drawing off means comprises, at each conductive member (2, 3, 4, 5), a respective longitudinal discontinuity region (6, 7, 8, 9) extending along a significant portion of electrical power transmission line length, being respectively symmetric with respect to the same longitudinal symmetry plane, said drawing off means (10, 13, 15, 17; 23; 30) being together displaceable at any point along said discontinuity regions (6, 7, 8, 9), keeping said symmetry with respect the same longitudinal symmetry plane.

2. Electrical power transmission line (1) according to claim 1, comprising two tubular conductive members.

3. Electrical power transmission line (1) according to claim 1, comprising three tubular conductive members.

4. Electrical power transmission line (1) according to claim 1, comprising four tubular conductive members (2, 3, 4, 5) .

5. Electrical power transmission line (1) according to claim 1, wherein the innermost conductive member (2) is massive .

6. Electrical power transmission line (1) according to claim 1, wherein the pass-through sections of each conductive (2, 3, 4, 5) member are uniform, for having the same linear resistance along each conductor.

7. Electrical power transmission line (1) according to claim 1, wherein the pass-through sections of each conductive member (2, 3, 4, 5) are variable from the inner to the outer, for decreasing the thermal stresses of the electric power transmission line.

8. Electrical power transmission line (1) according to any of the preceding claims, wherein the conductive members (2, 3, 4, 5) have a square or rectangular section .

9. Electrical power transmission line (1) according to claim 5, wherein the conductive members (2, 3, 4, 5) are manufactured by bending a sheet in conductive material.

10. Electrical power transmission line (1) according to claim 5, wherein the conductive members (2, 3, 4, 5) are manufactured by extrusion.

11. Electrical power transmission line (1) according to claim 5, wherein the conductive members (2, 3, 4, 5) are manufactured by welding of parts obtained by bending or extrusion .

12. Electrical power transmission line (1) according to any of the preceding claims, wherein said longitudinal discontinuity regions comprises a longitudinal continuous slot (6, 7, 8) .

13. Electrical power transmission line (1) according to claim 12, wherein the slots (6, 7, 8) extend along the whole length of the electrical power transmission line (D •

14. Electrical power transmission line (1) according to claim 12, wherein said slots (6, 7, 8) are placed at the centre of the conductive member surfaces.

15. Electrical power transmission line (1) according to claim 12, wherein said slots are placed at the connection corner of two surfaces of each conductive member (2, 3, 4, 5) .

16. Electrical power transmission line (1) according to any of the preceding claims, wherein said drawing off members (10, 13, 15, 17) comprise a flat plate or strip perpendicularly extending to the conductive member surface .

17. Electrical power transmission line (1) according to claim 16, wherein said drawing off members (10, 13, 15) have, at the opposite and/or external surfaces thereof, an insulating layer (11, 14, 16) .

18. Electrical power transmission line (1) according to claim 16, wherein, at each drawing off strip (23) except for the outermost one, insulated spacer (28) are provided, in a material having a proper mechanical and dielectric strength, inserted between drawing off plates (10, 13, 15 e 17) acting for spacing and assembling the latter ones.

19. Electrical power transmission line (1) according to claim 17, wherein said drawing off members (10, 13, 15, 17) and the respective insulating layers (11, 14, 16) are arranged so as to leave uncovered the end of each drawing off member (10, 13, 15, 17) and to form continuous strips longitudinally placed.

20. Electrical power transmission line (1) according to claim 16, wherein the conductive members (2, 3, 4, 5) are open at a wall thereof and have, at the edges thereof, two symmetric fin (29) to which contact members (23) are connected.

21. Electrical power transmission line (1) according to claim 16, wherein the longitudinal slots are formed on opposite surfaces of the electrical power transmission line (1) .

22. Electrical power transmission line (1) according to claim 20 or 21, wherein the longitudinal slots have a uniform width.

23. Electrical power transmission line (1) according to the preceding claims 16, 21 or 22, wherein the drawing off means comprises a contact member (30) substantially T-shaped, comprising a head (31), apt to establish a contact with a the edges (36) of the slot, and a stem (32), possibly provided with an insulated collar, apt to projects from the electrical power transmission line (1) for allowing the assembling of electrical wiring.